It's a known issue, it has already been forwarded to our developers.
You can downgrade, if you wish, to PathFinder 7.4.1. It should work fine on this version.
Here's the link to the compatible version: https://www.dropbox.com/s/hw64ywf3fbafis2/PF_7.4.1_%281704%29.zip?dl=0
We also recommend disabling the automatic update checker in Path Finder > Preferences > General.
Please note that this solution is compatible with Sierra (macOS 10.12) only.
If you decide to proceed, let us know how it goes.
Don't hesitate to contact us should any questions arise.
It didn't help to downgrade but I have to change my story a bit. The "automatically resize" do function on all files as long as I rest inside the folder or move to a folder above. But when I return to the down folder again the preset settings will be gone. The preview shows up again - tiny. Very irritating.
Please follow the instruction and check if the issue still persists:
Open your terminal and paste the following command to check if Path Finder has been slapped with the quarantined extended attribute:
xattr /Applications/"Path Finder.app"
If you see com.apple.quarantine returned as output from that last command, then go ahead and run this next command:
xattr -d com.apple.quarantine /Applications/"Path Finder.app"
You won't get any feedback or output from that command, but that's okay because you can just run the first command again to see for yourself if the com.apple.quarantine attribute shows up again. It shouldn't, and now Path Finder is freed from Apple quarantine jail. Restart your PathFinder now.
I did as you suggested but afterwards I had a empty sidebar instead (i wrote about it here) http://support.cocoatech.com/discussions/problems/93814-empty-sidebar.
But I solved that so now I am back with a totally new PF7 7.6.2 (without any cashes) and the preview matter is different now.
It's still the same problem if I chose "resize automatically". The setting will stay on inside the folder or folder above. But if I chose "real size" instead the setting will stay on for longer. On this setting I can't see a clear pattern on when the setting falls out. Maybe there is a RAM issue?
It had been better if the default setting for the preview window hade been "automatically". Then I would have seen the .pdf as a preview and not as a thumbnail.
I really hope you can fix this problem because PF's preview windows is the feature that make PF my choice of Finder alternative.
I want to add something. When I say preview window I mean the one in a right or bottom sidebar (see image)
So it's not the preview in the column view I have problems with because that one has "automatically" as default.
As I mentioned above, it is, unfortunately, a known issue.
We've already reported it to our developers. They are currently working on a new version of PathFinder.
It's currently scheduled for the end of April. Chances are this issue will be fixed there.
Sorry for the temporary inconvenience.
Please feel free to write us back and we will be happy to assist you.